Electrochemical detection of 3-methyl-4-nitrophenol (MNP) in direct phenol oxidation occurs at high potentials and generally leads to progressive passivation of the electrochemical sensor. This study describes the use...Electrochemical detection of 3-methyl-4-nitrophenol (MNP) in direct phenol oxidation occurs at high potentials and generally leads to progressive passivation of the electrochemical sensor. This study describes the use of a carbon fiber microelectrode modified with a tetrasulfonated nickel phthalocyanine complex for the detection of MNP at a lower potential than that of direct phenol oxidation. The MNP voltammogram showed the presence of an anodic peak at -0.11 V vs SCE, corresponding to the oxidation of the hydroxylamine group generated after the reduction of the nitro group. The effect of buffer pH on the peak current and SWV parameters such as frequency, scan increment, and pulse amplitude were studied and optimized to have better electrochemical response of the proposed sensor. With these optimal parameters, the calibration curve shows that the peak current varied linearly as a function of MNP concentration, leading to a limit of detection (LoD) of 1.1 μg/L. These results show an appreciable sensitivity of the sensor for detecting the MNP at relatively low potentials, making it possible to avoid passivation phenomena.展开更多
Capillary electrophoresis (CE)/electrochemical detection (EC) for the simultaneous determination of hydrazine and isoniazid has been developed. The electrochemical method uses a novel modified electrode dispersed with...Capillary electrophoresis (CE)/electrochemical detection (EC) for the simultaneous determination of hydrazine and isoniazid has been developed. The electrochemical method uses a novel modified electrode dispersed with ultrafine platinum particles on the surface of a 30 mu m carbon fiber microelectrode. The unique characteristic of the Pt-particles modified carbon fiber microelectrode is its excellent stability. The current measurement for hydrazine is more sensitive than that of isoniazid. Selective determination of trace amount of free hydrazine in isoniazid and its formulation can be achieved at applied potential of 0.5 V.展开更多
A rapid and sensitive 1.5 order adsorptive stripping voltammetric method fordetendnation of trace mitoxantrone (MXT) is described. The accumulation behavior of MXT on amercury film ndcroelectrode was studied and the p...A rapid and sensitive 1.5 order adsorptive stripping voltammetric method fordetendnation of trace mitoxantrone (MXT) is described. The accumulation behavior of MXT on amercury film ndcroelectrode was studied and the possibility of carrying out 1.5 order differentialadsorptive stripping analysis using mercury-coated carbon fiber ndcroelectrode was demonstrated.Optimal conditions for 1.5 order differential voltammetry monitoring are described. The strippingpeak current is linearly proportional to the concentration of MAT in the range of 1.0×10-6 mol/L 1.0×10-9 and detection licit is 1.5×10-10 mol/L. The relative standard deviation (RSD) is 3.0% at5.0×10-8 (n=8). MXT can be detendned directly in biological samples at physiological levelswithout any separation procedure.展开更多
文摘Electrochemical detection of 3-methyl-4-nitrophenol (MNP) in direct phenol oxidation occurs at high potentials and generally leads to progressive passivation of the electrochemical sensor. This study describes the use of a carbon fiber microelectrode modified with a tetrasulfonated nickel phthalocyanine complex for the detection of MNP at a lower potential than that of direct phenol oxidation. The MNP voltammogram showed the presence of an anodic peak at -0.11 V vs SCE, corresponding to the oxidation of the hydroxylamine group generated after the reduction of the nitro group. The effect of buffer pH on the peak current and SWV parameters such as frequency, scan increment, and pulse amplitude were studied and optimized to have better electrochemical response of the proposed sensor. With these optimal parameters, the calibration curve shows that the peak current varied linearly as a function of MNP concentration, leading to a limit of detection (LoD) of 1.1 μg/L. These results show an appreciable sensitivity of the sensor for detecting the MNP at relatively low potentials, making it possible to avoid passivation phenomena.
基金Project supported by the National Natural Science Foundation of China.
文摘Capillary electrophoresis (CE)/electrochemical detection (EC) for the simultaneous determination of hydrazine and isoniazid has been developed. The electrochemical method uses a novel modified electrode dispersed with ultrafine platinum particles on the surface of a 30 mu m carbon fiber microelectrode. The unique characteristic of the Pt-particles modified carbon fiber microelectrode is its excellent stability. The current measurement for hydrazine is more sensitive than that of isoniazid. Selective determination of trace amount of free hydrazine in isoniazid and its formulation can be achieved at applied potential of 0.5 V.
文摘A rapid and sensitive 1.5 order adsorptive stripping voltammetric method fordetendnation of trace mitoxantrone (MXT) is described. The accumulation behavior of MXT on amercury film ndcroelectrode was studied and the possibility of carrying out 1.5 order differentialadsorptive stripping analysis using mercury-coated carbon fiber ndcroelectrode was demonstrated.Optimal conditions for 1.5 order differential voltammetry monitoring are described. The strippingpeak current is linearly proportional to the concentration of MAT in the range of 1.0×10-6 mol/L 1.0×10-9 and detection licit is 1.5×10-10 mol/L. The relative standard deviation (RSD) is 3.0% at5.0×10-8 (n=8). MXT can be detendned directly in biological samples at physiological levelswithout any separation procedure.
